The following description relates to a power converter for a fuel cell which can perform a diagnosis and a load leveling of the fuel cell, and a method of controlling the same.
Fuel cell technology is new environment-friendly future energy technology generating electric energy from a material which abundantly exists in the Earth such as oxygen and hydrogen, and is one among technologies in which the attention has been focused recently. The fuel cell directly converts chemical energy the oxygen and the hydrogen have into the electric energy by an electrochemical reaction, and obtains the electric energy of high efficiency without causing pollution since the oxygen is provided to a cathode and the hydrogen is provided to an anode, and the electrochemical reaction is proceeded in the form of an inverse reaction of a water electrolysis. Since the fuel cell is free from a limitation of a Carnot cycle acting as a limitation in a conventional heat engine, the fuel cell can have efficiency which is equal to or more than 40%, and since the material emitted as described above is only water, there is no concern of the pollution, and since a part moving mechanically is not needed unlike the conventional heat engine, there are various advantages in which there is no noise, etc. Accordingly, various kinds of technologies and studies related to the fuel cell are actively being carried out. However, in order to implement the fuel cell as an actual power supply system, it is necessary to compensate various problems of the fuel cell. First, since an overload withstand of the fuel cell is small, the fuel cell is largely used as a hybrid system connecting another energy storage device. The hybrid system is needed in order to manage by dividing an abrupt load change or a load exceeding a rated capacity of the fuel cell, and is a system using an auxiliary energy storage device for a high output for a short time besides the fuel cell, a battery or a super capacitor, etc. being used as the auxiliary energy storage device, and there is a cost reducing effect since the auxiliary energy storage device has a smaller cost about by 1/100 than the fuel cell. Further, after configuring the hybrid system by connecting the fuel cell and the auxiliary energy storage device, constant power is continuously output from the fuel cell, when the power is left, the energy storage device is charged using the surplus power, and when the power is insufficient, a load leveling method in which the energy storage device subsidiarily outputs the insufficient power is applied. Further, since the fuel cell has a problem in which reliability of the system configured together depends on a state of the fuel cell, an evaluation through a periodic test of the fuel cell is needed. In order to evaluate a lifespan of the fuel cell, an offline method in which the fuel cell is separated from the system or an independent measurement device is attached to the outside, etc. can be applied, but the method is inefficient and inconvenient.
The present invention is directed to providing a power converter for a fuel cell which can perform a load leveling of the fuel cell and diagnose a lifespan of the fuel cell, and a method of controlling the same.